Sahih Ibn Khuzaymah

And the explanation that placing both hands on both knees abrogates the act of *tadbeeq*—because the act of *tadbeeq* was earlier, and the act of placing both hands on the knees came after it. Therefore, the earlier act is abrogated and the later act is the abrogator.

Sayyiduna Abdullah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) taught us the prayer, so « اللهُ أَكْبَرُ » said, and when he intended to bow (ruku‘), he joined his two hands and placed them between his knees, then performed ruku‘. When Sayyiduna Sa‘d (may Allah be pleased with him) heard of this, he said, "My brother has spoken the truth; this is how we used to do it, then we were commanded regarding it," meaning (to) hold the knees with both hands.